Artist’s impression of Diluvicursor Pickeringi dinosaur, which ran on strong hind legs and weighed 3 or 4 kilos.
Photograph: Supplied by Matt Herne, University of Queensland

More than 10 years after fossils were discovered sticking out of a rock platform in Victoria’s remote south-west, scientists have identified a new dinosaur that once roamed the “lost world” between Australia and Antarctica.

Foot and tail fossils found in 113-million-year-old rocks near Cape Otway in 2005 have led to the discovery of a turkey-sized herbivore which lived in the Australian-Antarctic rift valley.

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The fossil was buried along with flood-transported tree stumps, logs and branches in deep scours at the base of what was once a powerful river.

Matt Herne from the University of Queensland’s School of Biological Sciences said the discovery helped demonstrate the diversity of the dinosaur life that populated the ancient rift valley that once connected Australia to Antarctica.

“It shows for the first time that there were at least two distinct body-types among closely related ornithopods, small, two-legged grazing dinosaurs, in this part of Australia,” he said.

“One called Leaellynasaura was lightly built with an extraordinarily long tail, while the other, Diluvicursor, was more solidly built, with a far shorter tail.”

Bordered to its east by a massive active volcanic mountain range that fed sediment into the valley via a series of large rivers, scientists believe the valley was likely to have been a “lush, fertile environment”.

“We don’t know the exact climatic conditions. Some scientists believe it would have been really quite cold because of its location on the edge of the Antarctic circle, but others, and I’m one, think it was probably warmer, maybe a climate similar to Sydney.”

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After discovering the fossils in 2005, Herne said it had taken until now to fully understand the geology of the valley.

“Much of the fossil vertebrate material from this site has yet to be described, so we hope to discover further dinosaur species, specimens and other exciting animals there,” he said.

Among the other discoveries were rodent-sized mammals, turtles, and possibly a species of flying reptile.

“Understanding the ecology of these dinosaurs – what they ate, how they moved, where they roamed – based on the interplay between anatomy and the environment presents exciting challenges for future research,” Herne said.